Camshaft adjustment devices, in particular hydraulic camshaft adjustment devices are well known in the state of the art. The hydraulic camshaft adjustment device comprises an impeller having blades molded in or arranged on. The blades are located in hydraulic chambers, which are formed in an outer rotor. By appropriately applying hydraulic fluid to the corresponding side of the hydraulic chambers an adjustment of the inner rotor (connected to the camshaft) relative to the outer rotor can be achieved between an “early stop” and a “late stop”. Thereby, the flow of hydraulic fluid is controlled by means of an electrically activated directional valve. The transmission of the rotary motion of the crankshaft to the outer rotor is performed by a gearwheel mounted non-rotatably to the outer rotor.
A camshaft adjustment device of the mentioned kind is known from the German patent application DE 39 29 619 A1. The adjustment of the relative rotational position between crankshaft and camshaft is also achieved by hydraulic means. To constantly provide hydraulic fluid of sufficient pressure, a pressure reservoir with substantially cylindrical form is arranged on a cover element. The pressure reservoir radially extends away from the housing element. Through an also radially extending connection bore between the cover element and the pressure reservoir pressurized fluid can be channeled to the pressure reservoir to move a spring-biased piston by one piston stroke. The pressurized fluid then is available to the pressure reservoir with predetermined pressure. As needed, pressurized fluid can be removed again, wherein the spring moves the piston and thus fluid pressure is kept at a constant rate.
One disadvantage of the described device is that the manufacturing effort for the cover element and the pressure reservoir is relatively high and a plurality of cutting operations is usually required until completion. A further disadvantage is that the described kind of construction causes a device with relatively huge dimensions, which can't always be put into practice due to limitedly available space.